The present invention relates to a developing apparatus for a diazo copying machine.
In a diazo copying machine, a copy sheet is developed by passing the sheet through a developing chamber filled with ammonia vapor. A heater, for example comprising three to five sheathed heating elements, are provided in the developing chamber to maintain the ammonia in vapor form. Typically, an inlet chamber and an outlet chamber are provided adjoining the developing chamber which are separated from the developing chamber by sheet feed rollers. A problem has heretofore remained in such developing apparatus in that when the copying machine is initially energized, the temperature distribution in the developing chamber is uneven and the temperature is lower at the ends than in the center thereof. As a result, the temperature in the developing chamber near the feed rollers separating the developing chamber from the inlet chamber is often too low to prevent condensation of water vapor contained in the developing chamber. In addition, since the inlet chamber is indirectly heated, the temperature therein is similarly too low to prevent condensation of water vapor. Water vapor thereby condenses on the feed roller and is transferred to copy sheets as they are fed by the feed rollers from the inlet chamber into the developing chamber. This condensed water severely degrades the developing process such that extremely blurred copies are produced.